In the field of low silver coverage photographic materials intended for redox amplification (RX) processes it has been proposed to use a fixer comprising an alkali metal sulfite as fixing agent and a bleach comprising a peroxide and an alkali metal halide. These proposals are described in European Publications. 0,540,619, 0,506,909, and 0,470,083.
Such fixers and bleaches are more environmentally friendly than thiosulfate fixers or bleaches containing ferricyanide ions or complexes of iron as the bleaching agent.
The silver level, however, in conventionally processed materials is much higher than those used with RX processes hence process times are expected to be longer when they are applied to conventional materials. For example if there is more silver halide to remove, more time will be taken for the fixing step.
The silver from the image can be removed by a conventional bleach-fix but this contains iron(III) EDTA that is considered a problem in the environment when sewered.
A peroxide bleach immediately following the developer results in increased density caused by continued redox amplification that may result in staining. It is also difficult to maintain the desired sensitometry in such circumstances. This problem can be alleviated by incorporating an acid stop or wash bath after image formation.
When the silver level is higher than those used with the lowest silver RX materials it has been found that when they are processed through a process consisting of developer, sulfite fixer, peroxide rehalogenating bleach then wash, the silver chloride will print-up slowly in image areas and is very sensitive to darkening caused by sulfide in the atmosphere.
The problem is therefore to use a sulfite fixer and a peroxide rehalogenating bleach on color silver halide materials while retaining full bleaching and fixing without suffering from variations in the sensitometric keeping properties.